Method for producing lagtams



1951 o. WICHTERLE 7 METHOD FOR PRODUCING LACTAMS BY REARRANGEMENT OF CYCLIC KETOXIMES Filed Ifeb. 21, 1948 INVENTOR.

www-

Macaw? E va? Patented Oct. 30, 1951 '2,57s,37 i' METHOD FOR PRODUCING LAerAMs fiY REARRANGEMENT OF CYGLIC om" Winn e-1e, i'img ue, Czechoslovakia,

to Gheii' icke zavo'd'y na S ovens KE'rox:

podiiik, Biatislava; Czechoslotie'tkia A l p li cat igiijebi'ilari 21, Sferial 16,187

In czcll bs ldi lakia. Malh' 8, 1946' 11 Claims. (01. 260-2393) either separately or inthefo'rm of the sulphuric acid solution of the oxime, into a preheated sulphuric acid solution containing preformed lacta'fil at a regulated rate of speed so as toperm'it' the dissipation of the heat evolved during the rearrangement reaction. The cooling rhustnet s6 intensive so as to r'educethe temperature below a certain value at which" the rearrang'erneiit" reaction takes place. One of the known rnethd's' of externally cooling utilizes a liquid, boiling at an appropriate temperature, in the jacket of the reaction kettle. Another method of cooling con;-' sists in mixing the reaction solution diretlj with the cooling liquid such as acetic acid, the vapors of which are cooled and conde'r'is'ed in a reflux condenser. w h The present invention comprises the use of an inert solvent, for the-keto dine which is an: niiscible with water and sulphuric acid-such carbon disulphide, a; hydrocarbon or a hydr carbon derivative, and in directing all or a per tion of the condensed solvent fromthe reflux cooler through a device where in the cyclic ketoxime is dissolved, and'in further" directing such oxime solution into a reaction kettle into" which sulphuric acid is introduced siniultaneous 1y, the sulphuric acid solution of the Iact'ani be iiig continuously withdrawn at another place of the kettle. Simple or halogenated hvdrocab b'bns, such as benzene, carbon tetrachlorideand the like may be successfully used as inert solvents forthis purpose.

The use of the inert solvent permitsan effect tive' control of the-rearrangementreactio'r'ithus enabling the'prod'uction of the lacta'ms arr-an industrial scale; Bi'usihg a'- solvent immiscible with water and-sulphurie acichit is possible separate the cyclic ketox-iines directlyirom' the aqueousmixtures in which they have been fbfihtfithefhfir dispfisi'fig With'the" necessity 'r met odiaceording to the invention will described in for'rhof a example in comi tion with the" accompanyin diagrammatic drawmai w i i V a gig. 1 showsa general plan of the apparatus; an

fi aa ag Sishow wear-mam forms of see" torn' s1 A 7 sulphuric acid'contai-nin'g1 some the levelfr pres ted by the broken sothat the partition I"? efiiergesa :bit.'- shape of this partit on war-1 which serveew lengthen the courseof asset of thereactiori liii' i liid iS SHfivfiiK- Fig: 2: livihg hitei? the solu n in the r e upto the rearrangemefifi temperature; up to" smut 60:70 0., thehea; "it? is stbpiied and carbon tetrachloride 15 led urieugir the pipe; {and the nezzle" 9' over the c cle: hexanone' o'fii-iiie situated in t e corit'aiher' lo" oii al'pe 'ffdfatd bdttoifi l l, Wheiifi the OXfn'ition is obtained? The dosing pump 4 row the obtained ox'h'n'e soli-itioh through the no 3'ifit0'the kettle l. The'finelif'displsdoxlifi begins to rearrange;'causing the solve" 4 due to' the releasedheat or the reac-tio 1 vapors of the solvent are condense'di'ri therefiux cooler" I 2. The flififiel IS 'I''aClS Qidf the condensed solvent thr'ci'ugh' the'nlaiii r4 the container ill wherein the dissdllitidrr Of Q.- further ameu'iitof theoxinie' takes place? upon the temperature of the solvent so that the process can also be influenced by means of cooling or heating the pipe M. The reaction product, which is a highly concentrated sulphuric acid solution of the lactam is withdrawn through the-overfiow-outlet 1 into the kettle IS, the bottom ofwhich is provided with a similar partition wall like the bottom of the kettle I.

This kettle or container 18 is heated up to 80-85 C. in order to rearrange any .traces of the oxime which may be present due to having boiled over partition wall 6 into outlet 1. Simultaneously, any remaining solvent is vaporized, said vapors being led'through'a thermi cally isolated pipe 19 into the top of the kettle I. It is also possible to condense these vapors in a separate cooler and to lead this condensate into the pipe 8. I

This invention is not limited to the above described example only. The device may be built ina more simple or in a more complex manner. Any inert fluid which dissolves cyclic oximes, is immiscible with sulphuric acid and wa-' ter, and boils between 40-160 C. at atmospheric pressure'may be used as solvent. Noncorrosive solvents are preferred. The oxime solution may be added directly to the refluxed solvent in order to dilute the oirime before the rearrangement reaction. r The term the rearrangement temperature" signifies any suitable temperature at which the specific oxime, under given conditions, rearranges instantaneously." This value does not depend only upon the concentration of the hydrate of sulphur trioxide employed, but also depends upon several other factors such as the kind of oxime, its concentration, the apparatus employed, etc. The arrangement of the device itself may be changed indifferent ways, such as providing the reaction kettle with a stirring device, in order to prevent the separation of the two immiscible liquids into coherent layers by means of virogous stirring, so that the progress of the reaction is entirely isothermic. In this case, the bottom partition wall may be dispensed with or it may be arranged at a suitable height according to the Fig. 3 wherein one or more stirring devices may be arranged in the wide, deep trough. The electric motor driving the worm screw I! may be switched on atv the moment when the weight of the oximeon the perforated bottom I I falls below a certain value.

; WhatI claim is: a

1. A continuous method of producing lactams from cyclic ketoximes which comprises dissolving said ketoxime in an inert solvent having a boiling point between 40 C.l60 C. which is immiscible with water and with sulfuric acid, introducing said ketoxime Solution into a P heated solution of sulfuric acid whereby rearrangement to the lactam takes place with the evolution of heat evaporating said inert solvent thereby controlling the heat evolved during the rearrangement reaction, recovering the lactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the condensed solvent to dissolve further quantities of ketoxime.

2. A continuous method of producing caprolactams from cyclohexanone oxime which comprises dissolving said cyclohexanone oxime in an inert solvent havin a boiling point between 40 C.-l60 C. which is immiscible with water and with sulfuric acid, introducing said cyclohexanone oxime solution into a preheated solu- 4 tion of sulfuric acid whereby rearrangement to the caprolactam takes place with the evolution of heat, evaporating said inert solvent thereby controlling the heat evolved during the rearrangement reaction, recovering the caprolactam from the reaction mixture-,5 condensing ,the vapors of said inert solvent and recycling the condensed solvent to dissolve further qualities of cyclohexanone oxime.

. 3. A continuous method of producing lactams from cyclic ketoximes which comprises dissolving said ketoxime in an inert solvent consisting of chlorinated hydrocarbons having a boiling pointbetween 40 C.-l60 C. which is immiscible with water and with sulfuric acid, introducing said ketoxime solution into a preheated solution of sulfuric acid whereby rearrangement to the lactam takes place with the evolution of heat, evaporating said inert solvent thereby controlling the heat evolved during the rearrangement reaction, recovering the lactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the con-' densed solvent to dissolve further quantities of ketoxime.

4. A continuous method of producing lactams from cyclic ketoximes which comprises dissolving said ketoxime in an inert solvent consist-' ing of carbon teterahchloride having a boiling point between 40 C.- C. which is immiscible with water and with sulfuric acid, introducing said ketoxime solution into a preheated solution of sulfuric acid whereby rearrangement to the lactam takes place with the evolution of heat, evaporating said inert solvent thereby controlling the heat evolved during the rearrangement reaction, recovering the lactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the condensedsolvent to dissolve further quantities of ketoxime.

5. A continuous method of producing lactams from cyclic ketoximes which comprises dissolving said ketoxime in an inert solvent consisting of a hydrocarbon having a boiling point between 40'" C.-160 C. which is immiscible with water and with sulfuric acid, introducing said ketoxime solution into a preheated solution of sulfuric acid whereby rearrangement to the lactam takes place with the evolution of heat, evaporating said inert solvent thereby controlling the heat evolved dur-' ing the rearrangement reaction, recovering the lactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the con-1 densed solvent to dissolve further quantities of ketoxime.

6. A continuous method of producing caprolactams from cyclohexanone oxime which comprises dissolving cyclohexanone oxime in an inert solvent consisting of chlorinated hydrocarbons having a boiling point between 40 C.-160 C.

which is immiscible with water and with sulfuric.

acid, introducing said cyclohexanone oxime solution into a preheated solution of sulfuric acid whereby rearrangement to the caprolactam takes I place with the evolution of heat, evaporating said inert solvent thereby controlling the heat evolved during the rearrangement reaction, recovering the caprolactam from the reaction mixture, condensing the vapors of said inert solvent and re- ;cycling the condensed solvent to dissolve further quantities of cyclohexanone oxime.

7. A continuous method of producing caprolactam from cyclohexanone oxime which comprises dissolving cyolohexanone oxime in an inert solvent consisting of carbon tetrachloride having a boiling point between 40 C.-160 C. which is immiscible with Water and with sulfuric acid, introducing said cyclohexanone solution into a preheated solution of sulfuric acid whereby rearrangement to the caprolactam takes place with the evolution of heat, evaporating said inert solvent thereby controlling the heat evolved during the rearrangement reaction, recovering the caprolactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the condensed solvent to dissolve further quantities of cyclohexanone oxime.

8. A continuous method of producing caprolactams from cyclohexanone oxime which comprises dissolving cyclohexanone oxime in an inert solvent consisting of hydrocarbon having a boiling point between 40 C.-160 C. which is immiscible with water and with sulfuric acid, introducing said cyclohexanone oxime solution into a pre heated solution of sulfuric acid whereby rearrangement to the caprolactam takes place with the evolution of heat, evaporating said inert solvent thereby controlling the heat evolved during the rearrangement reaction, recovering the caprolactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the condensed solvent to dissolve further quantities of cyclohexanone oxime.

9. A continuou method of producing lactams from cyclic ketoximes which comprise dissolving said ketoxime in an inert solvent having a boiling point between 40 C.-160 C. which is immiscible with water and with sulfuric acid, introducing said ketoxime solution into a preheated solution of sulfuric acid whereby rearrangement to the lactam takes place with the evolution of heat, evaporating said inert solvent and simultaneously refluxing a regulated amount of said inert solvent into the reaction mixture thereby controlling the heat evolved during the rearrangement reaction, recovering the lactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the condensed solvent to dissolve further quantities of ketoxime.

10. A continuous method of producing caprolactam from cyclohexanone oxime which comprises dissolving said cyclohexanone oxime in an inert solvent consisting of carbon tetrachloride having a boiling point between 40 C.160 C. which is immiscible with water and with sulfuric acid, introducing said cyclohexanone oxime solution into a preheated solution of sulfuric acid whereby rearrangement to the caprolactam takes inert solvent and simultaneously refluxing a regulated amount of said inert solvent into the re action mixture thereby controlling the heat evolved during the rearrangement reaction, recovering the caprolactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the condensed solvent to dissolve further quantities of cyclohexanone oxime.

11. A continuous method of producing caprolactam from cyclohexanone oxime which comprises dissolving said cyclohexanone oxime in an inert solvent consisting of a hydrocarbon having a boiling point between 40160 C. which is immiscible with water and with sulfuric acid, introducing said cyclohexanone oxime solution into a preheated solution of sulfuric acid whereby rearrangement to the caprolactam takes place with the evolution of heat, evaporating said inert solvent and simultaneously refluxing a regulated amount of said inert solvent into the reaction mixture thereby controlling the heat evolved during the rearrangement reaction, recovering the caprolactam from the reaction mixture, condensing the vapors of said inert solvent and recycling the condensed solvent to dissolve further quantities of cyclohexanone oxime.

OTTO WICHTERLE.

REFERENCES CITED The following references are of record in the file of thispatent:

UN ITED STATES PATENTS OTHER REFERENCES Combined Intelligence Objectives Sub-Committee Report (Item No. 22; File No. XXVI-53): Manufacture of Caprolactam, I. G. Farbenindustrie Leunawerke, Merseburg (Declassified by authority of the Joint Chiefs of StaflE in List No. 1, February 1, 1946) 6 pages. 

1. A CONTINUOUS METHOD OF PRODUCING LACTAMS FROM CYCLIC KETOXIMES WHICH COMPRISES DISSOLVING SAUD KETOXIME IN AN INERT SOLVENT HAVING A BOILING POINT BETWEEN 40* C.-160* C. WHICH IS IMMISCIBLE WITH WATER AND WITH SULFURIC ACID, INTRODUCING SAID KETOXIME SOLUTION INTO A PREHEATED SOLUTION OF SULFURIC ACID WHEREBY REARRANGEMENT TO THE LACTAM TAKES PLACE WITH THE EVOLUTION OF HEAT EVAPORATING SAID INERT SOLVENT THEREBY CONTROLLING THE HEAT EVOLVED DURING THE REARRANGEMENT REACTION, RECOVERING THE LACTAM FROM THE REACTION MIXTURE, CONDENSING THE VAPORS OF SAID INERT SOLVENT AND RECYCLING THE CONDENSED SOLVENT TO DISSOLVE FURTHER QUANTITIES OF KETOXIME. 